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PEER REVIEWED

Microstructure and Properties of TiC-Reinforced Ti2Ni/Ti5Si3 Eutectic-Based Laser Cladding Composite Coating Xinmeng Sui1 • Jian Lu2 • Xian Zhang1 • Lin Sun1 • Weiping Zhang1

Submitted: 25 May 2020 / in revised form: 4 August 2020  ASM International 2020

Abstract Titanium alloys have high specific strength and excellent high temperature and corrosion resistance but low hardness and poor wear resistance. In this study, TiC-reinforced Ti2Ni/Ti5Si3 eutectic matrix composite coatings were fabricated on TC21 titanium alloy substrates by laser cladding. The phase composition and microstructure of the coating with micro- or nano-sized SiC addition as well as the microhardness and wear resistance of the coatings were evaluated. The analysis showed that the composite coatings were mainly made up of TiC, TiNi, Ti5Si3, and Ti2Ni phases, the TiC phase being distributed on the eutectic Ti2Ni/Ti5Si3 phase. The coatings with nano-SiC addition exhibited better coating quality, and higher microhardness and wear resistance than the coatings with micro-SiC addition. The better properties of the coating with nano-SiC addition were mainly attributed to the larger amount of the TiC hard-reinforcing phase and a more compact microstructure. The predominant wear mechanism of the coating with micro-SiC addition was adhesive wear, while it was abrasive wear for the coating with nano-SiC addition. This study should provide an insight into the development of Ti2Ni/Ti5Si3 eutectic matrix coatings. Keywords eutectic composite coating
microstructure
laser cladding
SiC
titanium alloys
wear resistance & Weiping Zhang [email protected] 1

Key Laboratory of Solidification Control and Digital Preparation Technology (Liaoning Province), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, People’s Republic of China

2

School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, People’s Republic of China

Introduction Titanium alloys have been extensively applied in aerospace, energy, chemical, and defense equipment due to their high specific strength, low density, and excellent high temperature and corrosion resistance (Ref 1-6). However, the inherent disadvantages (i.e., low hardness and poor wear resistance) of titanium alloys hinder their further promotion in advanced aircraft engines and weapons (Ref 7-11). Various surface modification methods, such as thermal spraying (Ref 12), physical vapor deposition or chemical vapor deposition (Ref 13, 14), plasma surface alloying (Ref 15), and laser cladding (Ref 16, 17), have the potential to overcome the disadvantages of titanium alloys. Among these methods, laser cladding of a composite coating to improve the hardness and wear resistance of titanium alloys has proven to be a predominant surface modification technology (Ref 18, 19). Recent studies suggest that fabricated eutectic composite coatings on titanium alloy surfaces to conquer the shortcoming of titanium alloys have attracted considerable atte